statistics: fix data race and error handling in stats load (#31301)

[ti-srebot]

cherry-pick #31301 to release-5.4
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/31490

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git push git@github.com:ti-srebot/tidb.git pr/31490:release-5.4-495525b262dd

---

What problem does this PR solve?

Issue Number: close #31237

Problem Summary:
This is targeted to fix the data race of writing & closing resultCh and incorrect error handling when paniked in finishWorking:
[2021-12-31T07:38:58.006Z] [2021/12/31 15:28:48.957 +08:00] [ERROR] [handle_hist.go:172] ["stats loading panicked"] [stack="goroutine 4028 [running]:\ngithub.com/pingcap/tidb/statistics/handle.(*Handle).handleOneTask.func1()\n\t/home/jenkins/agent/workspace/tidb_ghpr_unit_test/go/src/github.com/pingcap/tidb/statistics/handle/handle_hist.go:170 +0xa9\npanic(0x3c3f3c0, 0x4607ad0)\n\t/usr/local/go/src/runtime/panic.go:965 +0x1b9\ngithub.com/pingcap/tidb/statistics/handle.(*Handle).finishWorking(0xc02ec24b40, 0x3d, 0x4)\n\t/home/jenkins/agent/workspace/tidb_ghpr_unit_test/go/src/github.com/pingcap/tidb/statistics/handle/handle_hist.go:372 +0x106\ngithub.com/pingcap/tidb/statistics/handle.(*Handle).handleOneTask(0xc02ec24b40, 0xc04fd5df58, 0x7fc65c59dcf8, 0xc02e0df800, 0xc02d5310e0, 0x0, 0x0)\n\t/home/jenkins/agent/workspace/tidb_ghpr_unit_test/go/src/github.com/pingcap/tidb/statistics/handle/handle_hist.go:209 +0x6d4\ngithub.com/pingcap/tidb/statistics/handle.(*Handle).SubLoadWorker(0xc02ec24b40, 0x46f2848, 0xc02e0df800, 0xc02d5310e0, 0xc02e4a6488)\n\t/home/jenkins/agent/workspace/tidb_ghpr_unit_test/go/src/github.com/pingcap/tidb/statistics/handle/handle_hist.go:151 +0x125\ncreated by github.com/pingcap/tidb/domain.(*Domain).StartLoadStatsSubWorkers\n\t/home/jenkins/agent/workspace/tidb_ghpr_unit_test/go/src/github.com/pingcap/tidb/domain/domain.go:1305 +0x12b\n"]

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• AilinKid
• hawkingrei

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[ti-srebot]

/run-all-tests

[ti-srebot]

@chrysan please accept the invitation then you can push to the cherry-pick pull requests. Comment with /cherry-pick-invite if the invitation is expired.
https://github.com/ti-srebot/tidb/invitations

[hawkingrei]

/run-mysql-test

[AilinKid]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 41db7bb

[zhouqiang-cl]

/merge

[zhouqiang-cl]

/merge

[zhouqiang-cl]

/merge

[ti-chi-bot]

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